As bone cement for fixation of hard tissues, such as bones and cartilages, to artificial joints, bone filling materials used for osteoporosis therapy or the like, artificial bone materials, etc., various compositions for hard tissue repair have been studied in the past. For example, compositions containing polymethyl methacrylate, methyl methacrylate and benzoyl peroxide (polymerization initiator), compositions containing (meth)acrylate, an inorganic filler, such as calcium phosphate, and an organic peroxide, etc. have been studied (see, for example, patent literature 1).
Such compositions, however, undergo large-scale heat generation during curing and have a high risk of doing damage to the affected tissue.
When a composition for repair is used for hard tissues such as bones, it is a usual way that the components to form the composition are mixed in advance in a container or the like to prepare a composition and then the composition is applied to the surface of the affected part, taking into consideration workability, prevention of infection, etc. However, the state of the composition after mixing sometimes has influence on the workability during the application of the composition.
Since acrylic adhesives using an initiator containing an organoboron compound have low toxicity and low harmfulness and have high adhesive strength, development of them to dental applications has been promoted (see, for example, patent literature 2). However, if other medical applications, such as surgical applications, are intended, further improvement in handling stability or workability of the composition between mixing of the components and application to the application area has been sometimes required.